Operating Instructions for the SAMCO RIE800iPB Tool Owner: Pat Watson x8-4626, cell: 732 996 2713 Backup: Bert Harrop, cell 848 459 2542 Introduction The SAMCO International RIE800iPB is a state of the art inductively coupled plasma etcher (Figure 1). The tool specifications were fixed to enable users to etch Si and SiGe with a resist mask, strip photoresist, and etch SiO2 with a metal (Cr) mask. The tool is plumbed with SF6, C4F8, Ar, O 2, and CF 4. It possesses a He backside cooled electrostatic chuck that is temperature controlled with a chilled water circulator. Specimens are loaded into the process chamber by a robot arm through a load lock to minimize contaminants entering the process chamber and to protect users from hazardous etch byproducts. Wafers of 100mm, 150mm, or 200mm diameter can be processed in the system with an appropriate change of parts in the process chamber. Samples that are not of the standard wafer sizes listed must be mounted on a carrier wafer. There are 2 RF power sources to control the properties of the plasma. The first is a 3000W supply inductively coupled to the gas in the process chamber. It generates a high density of radicals and ions with only a small potential between the plasma and the wafer surface. An additional 500W source induces a potential between the chuck and the plasma just like a traditional RIE system. The advantage of this combination is that the plasma density and the substrate bias can be independently controlled. The system is controlled by an on-board computer and operated with a touch screen and a very simple jog dial. Users must log in to use the tool. A separate laptop computer acts as a data logger and may also be used for recipe editing and transfer.
Figure 1. The main unit of the PRISM MNFL Samco RIE800iPB etcher. The chilled water circulator and data log computer are on the right behind the main unit. Overview of the System The etcher consists of the: main unit, which houses the turbopump, electronics, RF sources and chambers (Fig. 1); circulator control, located on the table behind the main unit; data log laptop, located on the table behind the main unit; process dry pump and load lock dry pump, located behind the main unit; The main unit touch screen and jog dial control all of the tool operations except the chuck temperature (Fig. 2). The circulator temperature controller operates independently of the main unit and must be set manually. All of the other components, such as the pumps, are controlled through the main unit.
Emergency Off Touch Screen Main Power Jog Dial and Set Button Figure 2. The SAMCO 800iP computer interface with touch screen, jog dial, set switch, emergency off switch, and main power switch. There are 3 screen displays that are regularly used: The Main screen, showing the status of the sub-systems (Fig. 3) at the bottom. In the normal state, the status indicators at the bottom of the screen, PS, FS1, FS2, FS3, and FS4 should be highlighted. The Mode screen, where the user logs in and sets up process runs (Fig. 4). Normally, the tool is in Auto operation mode (region on lower right). The user logs in at the Login Menu region. Automatic recipes are set up in the Auto Sequence region. The Edit Screen, where the user edits recipes (Fig. 5). Normally, only the loop counts are modified.
Figure 3. The main screen. The 5 status indicators at the bottom, PS, FS1, FS2, FS3, and FS4, should be the only ones lit. Figure 4. The Set/Mode screen. There are 3 main sections, the login Menu, the Auto Sequence, and the Operation section. Normally, the operation mode should be Auto.
Figure 5. The Set/Edit screen. Users should only modify the loop count boxes in established recipes. Start up and Login 1) To operate the etcher, the user must first log in: a. Log in to the tool first through the on-line reservation system, then b. If it is not visible, select the Setup screen(s) by pressing the SET on the top left of the system touchscreen (Fig. 4). c. Press the Select User No. box on the touchscreen and, using the jog dial and set button, select the appropriate user ID number. d. Use the touch screen password digit selector up/down keys to enter the user password and press Login. 2) Sign in to the logbook with user ID and start time. 3) The system should normally be left with the load lock pumped down. To bring the load lock to atmosphere, a. use the Select Auto Sequence section of the SET/MODE screen (Fig. 4) and deselect all of the auto process steps except LLC Vent, which should be highlighted. b. Press the MAIN screen button, which displays a schematic of the system and then
c. press and hold RUN for a few seconds to start the venting process. The system beeps when the process starts and when it is complete. Mounting and Loading a Sample Since the electrostatic chuck must be protected at all times from the plasma, specimens that are not 100 mm, 150 mm, or 200 mm diameter wafers must be bonded to a carrier wafer. The default wafer size is 100mm (4 ). Please see the staff if the sample is larger than 100mm, since parts in the process chamber must be changed to accommodate it. 1) If a whole wafer is used, skip to step 4. A small sample (less than a 100mm wafer) must be mounted to a special carrier wafer. A 100 mm Si wafer covered with Kapton tape is typically used as the carrier. The carrier must be conductive to be electrostatically held to the chuck. 2) Clean and blow-off the exposed are of the carrier wafer with 2-propanol to remove any residue. 3) Using a small cleanroom swab, coat the carrier (or the back of the specimen) with a thin layer of a thermally conductive silicone grease. Make sure that as little grease is exposed as possible. Press the sample gently against the insulating side of the carrier to ensure good contact. Use thin strips of Kapton tape, cover the exposed regions of the carrier near the borders of the sample. 4) Check the back of the carrier to ensure it is free of any contaminants that could compromise the seal between the carrier and the He backside cooled chuck. 5) Open the load lock chamber door by pressing the two buttons on the panel just below the load lock (the chamber should now be at atmosphere) and place the carrier on the robot arm. Make sure it is properly centered. Place a cover ring, ceramic or quartz, over the carrier and center it as well. The cover ring will protect the small region of the chuck that is not covered by the carrier or the surrounding protective covering in the process chamber. Do not operate the etcher without a cover ring. Check to make sure that there are no obstructions or particles on the door o-ring and complementary surface, then close the load lock door by pressing the appropriate pair of buttons. Etching The user will generally use established etch recipes. Users may only modify the loop count of the main etch in the standard recipes. If other modifications are required, see the PRISM cleanroom staff so that they may copy the recipe of interest to another location for user modification. Please notify the staff of any major new recipe changes before trying them to prevent hazardous or damaging
situations. For instance, long runs using SF6 without some O2 can damage the turbopump. Do not turn off the electrostatic chuck or He backside cooling components of the recipes. 1) To edit a recipe, go to the edit subscreen in the set screen. Press the recipe box and select the recipe of interest with the jog dial/set button (Fig. 6). 2) Press the step number of interest and highlight (press) the loop count parameter boxes to modify them. Use the jog dial/set button to change the parameter values. 3) Check to make sure the data logging program is operating on the laptop computer. 4) Press the SET button on the touchscreen and then to the mode subscreen. Highlight all of the auto mode functions so that the device/carrier wafer is pumped down in the load lock, loaded into the process chamber, etched, removed from the chamber, and brought back to atmosphere (Fig. 5). 5) Select the recipe box on the touch screen and use the jog dial and set button to select the desired etch recipe. 6) Press the Main button on the touchscreen and then press Run. The tool will load etch and return the sample to the load lock. When the process is complete, the system will signal with a loud pair of beeps. Finishing Up 1) Open the load lock door, unload the cover ring and store it in the proper container. Unload the wafer or carrier. If using a carrier, remove the sample and wipe the carrier with 2-propanol to remove the silicone grease. The grease may be removed from the specimen by soaking and swabbing with warm 2-propanol, followed by a clean 2-propanol rinse and blowoff. 2) Close the load lock door. 3) In the Set/Mode screen, deselect all of the auto operations except LLC pump down (the first one) and Process. See Fig. 6. For the recipe, select 98, SClean (short clean) for etches that are 20 m deep or less. Choose 94, SLClean for etches greater than 20 m deep. For etch depths over 100 mm, LClean may be required. Contact the staff if you are etching for long periods. 4) Press main and run to pump down the load lock chamber and run the standard chamber clean. When complete, return to the set mode screen and logout by pressing logoff. Recipe SLClean takes over 40 minutes to complete, so be sure to allow for enough time. 5) Fill in the logbook with end time, recipe, data log file number, and any comments, results, etc. 6) Log out of the tool through the on-line reservation system.
Figure 6. A screen shot showing the final AUTO sequence that pumps down the load lock chamber and executes the clean recipes SClean (98) or SLClean (94).
Appendix A: Startup To start up the system from a power off condition, simply press the green Main On switch on the front of the unit. Once the computer boots up, login, select System Startup in the auto sequence box on the set/mode screen, then select Main, and press and hold Run. The system will automatically turn on each of the pumps. If an error occurs, press and hold Run again to continue the process. When complete (pair of beeps), the system vacuum system is ready. Turn on and set the circulator. Wait for 30 minutes for the chamber heaters to reach temperature. Appendix B: Shutdown Log in, goto set/mode, press System Shutdown on the auto sequence box, press Main and then press and hold Run. The system will safely turn off all pumps and isolate the chambers. When the sequence is complete (double beeps), turn off the main power with the red Main Off switch located on the front of the tool. Appendix C: Recovering after forgetting to log in to reservation system If you attempt to vent the load lock chamber without first logging in to the reservation system, the etcher will isolate the process chamber and remain in an error state. To recover, log in to the reservation system and to the tool and then from the main screen, select Buzz Off to turn off the alarm. Then follow the Startup instructions in Appendix A. The system should be ready in about 2 minutes. Revised gpw 5/10/2010, and on 9/2/2010, and on 5/76/2012